Silicon photonics is an emerging technology that enables fabrication of fast, low-cost and high-density photonic devices for a variety of uses and applications, notably in relation to optical network switching. Photonic switch fabrics, which are capable of switching optical signals without conversion to the digital domain, are an area of particular interest, especially for applications such as all-optical networks, data centers and optical interconnects.
A silicon photonic switch typically incorporates a number of optical waveguides of varying lengths, multiple optical switch cells, and multiple waveguide crossings having intersecting waveguides. A large switch matrix requires a large number of waveguide crossings. Achieving low optical loss and crosstalk due to waveguide crossings becomes particularly important for a large switch matrix. With silicon photonic components, the switch port count size may become limited by the total insertion loss and optical crosstalk. Low-loss, low-crosstalk waveguide crossings that can be fabricated using CMOS-compatible processes would thus be highly desirable.